4 sentences

1. 请按序排列这些文件。

   qǐng àn xù pái​liè zhè​xiē wén​jiàn.

   Please arrange these documents in order.

   Source: Dong Chinese Dictionary

2. 科学家已经完成了人类基因组的测序。

   kē​xué​jiā yǐ​jīng wán​chéng le rén​lèi jī​yīn​zǔ de cè xù.

   Scientists have completed the sequencing of the human genome.

   Source: Dong Chinese Dictionary

3. 他在书的序中阐述了创作动机。

   tā zài shū de xù zhōng chǎn​shù le chuàng​zuò dòng​jī.

   He explained his motivation for writing in the book's preface.

   Source: Dong Chinese Dictionary

4. 精彩的序曲为音乐会拉开了帷幕。

   jīng​cǎi de xù qǔ wèi yīn​yuè​huì lā​kāi le wéi​mù.

   A brilliant overture opened the concert.

   Source: Dong Chinese Dictionary